CODEWITHSUNDEEP
c++enumsswitch-statement
BotBotPgm
BotBotPgm

Reputation: 589

How do I use an enum value in a switch statement in C++?

I would like to use an enum value for a switch statement. Is it possible to use the enum values enclosed in "{}" as choices for the switch()"?

I know that switch() needs an integer value in order to direct the flow of programming to the appropriate case number. If this is the case, do I just make a variable for each constant in the enum statement?

I also want the user to be able to pick the choice and pass that choice to the switch() statement.

For example:

cout << "1 - Easy, ";
cout << "2 - Medium, ";
cout << "3 - Hard: ";

enum myChoice { EASY = 1, MEDIUM = 2, HARD = 3 };

cin >> ????

switch(????)
{
case 1/EASY:  // (can I just type case EASY?)
    cout << "You picked easy!";
    break;

case 2/MEDIUM:
    cout << "You picked medium!";
    break;

case 3/HARD: // ..... (the same thing as case 2 except on hard.)

default:
    return 0;
}

Upvotes: 58

Views: 225958

Answers (9)

maxim
maxim

Reputation: 31

You can cast enum with int.

enum TYPE { one, two, tree };

TYPE u;

u = two;

switch( int( u ) ){
        case one : 
        action = do_something ;
        break;
        case two:
        action = do_something_else;
        break;
}

Upvotes: 0

v010dya
v010dya

Reputation: 5848

You should keep in mind that if you are accessing a class-wide enum from another function, even if it is a friend, you need to provide values with a class name:

class PlayingCard
{
private:
  enum Suit { CLUBS, DIAMONDS, HEARTS, SPADES };
  int rank;
  Suit suit;
  friend std::ostream& operator<< (std::ostream& os, const PlayingCard &pc);
};

std::ostream& operator<< (std::ostream& os, const PlayingCard &pc)
{
  // Output the rank ...

  switch(pc.suit)
  {
    case PlayingCard::HEARTS:
      os << 'h';
      break;
    case PlayingCard::DIAMONDS:
      os << 'd';
      break;
    case PlayingCard::CLUBS:
      os << 'c';
      break;
    case PlayingCard::SPADES:
      os << 's';
      break;
  }
  return os;
}

Note how it is PlayingCard::HEARTS and not just HEARTS.

Upvotes: 3

Aman Singh
Aman Singh

Reputation: 31

I had a similar issue using enum with switch cases.

Later, I resolved it on my own....below is the corrected code, and perhaps this might help.

//Menu Chooser Programme using enum
#include <iostream>

using namespace std;
int main()
{
   enum level{Novice=1, Easy, Medium, Hard};
   level diffLevel = Novice;
   int i;
   cout << "\nEnter a level: ";
   cin >> i;

   switch(i)
   {
       case Novice:
           cout << "\nyou picked Novice\n"; break;

       case Easy:
           cout << "\nyou picked Easy\n"; break;

       case Medium:
           cout << "\nyou picked Medium\n"; break;

       case Hard:
           cout << "\nyou picked Hard\n"; break;

       default:
           cout << "\nwrong input!!!\n"; break;
   }
   return 0;
}

Upvotes: 3

radman
radman

Reputation: 18555

Some things to note:

You should always declare your enum inside a namespace as enums are not proper namespaces and you will be tempted to use them like one.

Always have a break at the end of each switch clause execution will continue downwards to the end otherwise.

Always include the default: case in your switch.

Use variables of enum type to hold enum values for clarity.

see here for a discussion of the correct use of enums in C++.

This is what you want to do.

namespace choices
{
    enum myChoice 
    { 
        EASY = 1 ,
        MEDIUM = 2, 
        HARD = 3  
    };
}

int main(int c, char** argv)
{
    choices::myChoice enumVar;
    cin >> enumVar;
    switch (enumVar)
    {
        case choices::EASY:
        {
            // do stuff
            break;
        }
        case choices::MEDIUM:
        {
            // do stuff
            break;
        }

        default:
        {
            // is likely to be an error
        }
    };

}

Upvotes: 18

Khaled Alshaya
Khaled Alshaya

Reputation: 96859

You can use a std::map to map the input to your enum:

#include <iostream>
#include <string>
#include <map>
using namespace std;

enum level {easy, medium, hard};
map<string, level> levels;

void register_levels()
{
    levels["easy"]   = easy;
    levels["medium"] = medium;
    levels["hard"]   = hard;
}

int main()
{
    register_levels();
    string input;
    cin >> input;
    switch( levels[input] )
    {
    case easy:
        cout << "easy!"; break;
    case medium:
        cout << "medium!"; break;
    case hard:
        cout << "hard!"; break;
    }
}

Upvotes: 8

Adam Holmberg
Adam Holmberg

Reputation: 7365

You're on the right track. You may read the user input into an integer and switch on that:

enum Choice
{
  EASY = 1, 
  MEDIUM = 2, 
  HARD = 3
};

int i = -1;

// ...<present the user with a menu>...

cin >> i;

switch(i)
{
  case EASY:
    cout << "Easy\n";
    break;
  case MEDIUM:
    cout << "Medium\n";
    break;
  case HARD:
    cout << "Hard\n";
    break;
  default:
    cout << "Invalid Selection\n";
    break;
}

Upvotes: 24

bornhusker
bornhusker

Reputation: 1

#include <iostream>
using namespace std;

int main() {

    enum level {EASY = 1, NORMAL, HARD};

    // Present menu
    int choice;
    cout << "Choose your level:\n\n";
    cout << "1 - Easy.\n";
    cout << "2 - Normal.\n";
    cout << "3 - Hard.\n\n";
    cout << "Choice --> ";
    cin >> choice;
    cout << endl;

    switch (choice) {
    case EASY:
        cout << "You chose Easy.\n";
        break;
    case NORMAL:
        cout << "You chose Normal.\n";
        break;
    case HARD:
        cout << "You chose Hard.\n";
        break;
    default:
        cout << "Invalid choice.\n";
    }

    return 0;
}

Upvotes: 0

Peter Ruderman
Peter Ruderman

Reputation: 12485

You can use an enumerated value just like an integer:

myChoice c;

...

switch( c ) {
case EASY:
    DoStuff();
    break;
case MEDIUM:
    ...
}

Upvotes: 50

Jeremy Friesner
Jeremy Friesner

Reputation: 73061

The user's input will always be given to you in the form of a string of characters... if you want to convert the user's input from a string to an integer, you'll need to supply the code to do that. If the user types in a number (e.g. "1"), you can pass the string to atoi() to get the integer corresponding to the string. If the user types in an english string (e.g. "EASY") then you'll need to check for that string (e.g. with strcmp()) and assign the appropriate integer value to your variable based on which check matches. Once you have an integer value that was derived from the user's input string, you can pass it into the switch() statement as usual.

Upvotes: 0

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